The development of high density ULSI circuits with sub-micron dimensions has lead to the requirement to remove unwanted contaminants from the surface of the wafers used in the production of structures such as high density chips along with the high density multichip assemblies constructed from these chips. This becomes especially difficult in examples such as a trench in the trench capacitor; deep contacts necessitated by stacked capacitors in dynamic random access memories (DRAMS); or the use of the damascene process in the production of copper metallurgy. High density assemblies e.g. those using flip chip or cube packaging also present significant cleaning challenges. One example of a type of material to be removed includes the residuals left from a film in which all or a portion of is to be removed. One example of such a film is a photo-resist. Another example of a type of material to be removed includes incidental contaminates.
Depending upon the type of contaminant, it may be attached to the surface by mechanisms such as chemical bonding, mechanical attachment, or a combination of chemical and mechanical mechanisms. The minimum dimensions of particles to be removed has continued to decrease as the minimum feature size has decreased. This has been aggravated by the fact that the vertical dimensions in the chips have not tended to shrink as fast as the horizontal dimensions thus making relatively deeper holes for contaminate particles to be lodged in. Further, in chip assemblies, the use of smaller diameter solder balls in C4 connections have reduced the vertical dimension between the chip and the substrate thus making the removal of contaminates from the space more difficult.
What is needed is an improved method for cleaning surfaces and structures in small dimensions such those produced in semiconductor manufacture.